title: Evaluation of the effects of age and pituitary pars intermedia dysfunction on corneal sensitivity in horses.
abstract: OBJECTIVE
  To determine effects of age and pituitary pars intermedia dysfunction (PPID) on corneal sensitivity in horses.
  
  
  METHODS
  20 adult horses allocated into 3 groups (PPID group, old [> 15 years old] horses with PPID [n = 5]; old group, old [> 15 years old] horses without PPID [9]; and young group, young [≤ 10 years old] horses without PPID [6]). All horses with PPID had hirsutism and abnormal fat deposition or laminitis; none of the old or young horses had hirsutism, abnormal fat deposition, or laminitis.
  
  
  METHODS
  A Cochet-Bonnet aesthesiometer was used to measure the corneal touch threshold (CTT) in both eyes of each horse. The nylon monofilament was applied at a maximum length of 60 mm to the central region of the cornea and length was decreased by 5-mm increments until a consistent blink response was elicited. Tear production was assessed in all eyes via the Shirmer tear test (STT).
  
  
  RESULTS
  Mean ± SD CTT was significantly greater for young horses (47.50 ± 4.52 mm) than for horses in the old (28.06 ± 5.72 mm) and PPID (21.5 ± 3.37 mm) groups. Old horses had significantly higher CTT values than did horses with PPID. The STT values were within the reference range for all groups and did not differ significantly among groups.
  
  
  CONCLUSIONS
  Corneal sensitivity decreased with both age and PPID. Because decreased corneal sensitivity is associated with impaired wound healing, increasing age and PPID may increase the risk for nonhealing or recurrent corneal ulcers in horses.
authors.affiliation: Department of Clinical Sciences, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA.
authors.forename: Chelsey
authors.initials: C
authors.lastname: Miller
authors.forename: Mary L
authors.initials: ML
authors.lastname: Utter
authors.forename: Jill
authors.initials: J
authors.lastname: Beech
mesh_terms: D000375:Aging; D000818:Animals; D003315:Cornea / Q000502:physiology*; D005260:Female; D006734:Horse Diseases / Q000209:etiology*; D006736:Horses; D008297:Male; D010900:Pituitary Diseases / Q000150:complications / Q000473:pathology / Q000662:veterinary*; D052716:Pituitary Gland, Intermediate / Q000473:pathology*